Automatic choke attachment for shotguns



May 24, 1960 1.. M. DENAUX, SR 3 AUTOMATIC CHOKE ATTACHMENT FOR SHOTGUNS 2 Sheets-Sheet 1 Filed Dec. 29. 1958 0 I2 Fig. 5 a 1 IN VEN TOR.

. g 1% :s L

Lou/s M. Denaux May 24, 19-60 L. M. DENAUX, SR 2,937,465

I 7 AUTOMATIC CHOKE ATTACHMENT FOR SHQTGUNS r Filed Dec. 29, 1958 2 Sheets-Sheet 2 Lou/1s M Denaux INVENTOR. N

o 7 BY This invention-relates in general to new and useful improvements in attachments for shotguns, and more specifically to an improved automatic choke attachment for shotguns.

' --In the use of the shotgun for hunting purposes, particularly birds in flight, it is'desired that the choke of the shotgun be varied between each shot. Inasmuch as the Shots are fired one after the other, the hunter does not have the opportunity to vary the choke manually.

For that reason, it is desired that the choke of the shotgun barrel be automatically varied as the ,shotgun is tired. Heretofore there have been devised many types of automatic shotgun chokes. However, the chokes in most instances have been impractical for mass production and many of those which are suitable for. commercial purposes are so constructed whereby they are either too expensive or too undependable.

' 'Itistherefore the primary object of this invention to provide an improved automatic choke attachment for shotguns, which choke attachment is of a very sirnple construction and thus may be economically manufactured and at the same time having very few moving parts so as to be dependable.

. Another object of this invention is to provide an improved automatic choke for shotguns, the automatic choke including a barrel adapter which has the end thereof provided with circumferentially' spaced longitudinal slits topermit the extreme end of the barrel adapter to be deformed to vary thechoke 'of' the barrel, atapered sleeve engaging the slitted .portion of the barrel adapter was to deform the barrel adapter, and means for advancing the tapered sleeve along the barrel adapter to automatically vary the. choke of the adapter.

Another object of this invention is to provide an. auto-. matic choke attachment for shotguns which employs a conical sleeve engaged with spring finger-like ends of a shotgun barrel, the sleeve being screw-threaded for longitudinal movement. and there being provided means for turning the sleeveinresponse to each firing of the shotgunzwhereby the choke of the shotgun barrel is auto matically varied.

I further object of this invention is to provide an automatic choke for shotgun barrels, the automatic choke employing a screw-threaded sleeve which has a conical 1 portion engaging a deformable part of a barrel exten .sion, the sleeve being driven by a member which is rot. tated in response to the firing of the shotgun, the memher having a connection with the sleeve of such a' nature whereby when the meniber'is'rotated in one direction, thesleeve" is' not driven, but when the me'mber is rotated in the opposite direction the sleeve is driven in order to advance the sleeve, the'memberrotating back and'forth with eachifiring of the shotgun. I

I 'The'setogether with other objects and advantages which will become'subsequently apparent reside in the details "ofconstruction-and operation as more fully hereinafter de'sc'ribed' and-claimed-referencebeing had to the acshows further the details of the automatic choke at.-

tachment; V V

Figure 4 is a top view of the automatic choke attachment and the shotgun barrel with a portion-of the shield for the operating mechanism of the automaticchoke attachment being removed and illustrating the operating mechanism thereof;

Figure 5 is a bottom plan view of the shotgun-attachment with portions of the shield being broken away and shows the connection between the operation member of the choke attachment and the barrel extension member; Figure 6 is an enlarged transverse sectional view taken substantially upon the plane indicated by the section line 6-6 of Figure 3;

Figure 7 is an enlarged transverse sectional viewtaken substantially upon "the plane indicated by the section line 7-7 of Figure 3;

Figure 8 is a longitudinal sectional view similar to Figure 3 and shows. the automatic choke attachmentin the fully choked position; and

Figure 9 is a plan view similar to' Figurel'4' and shows the choke attachment in the fully choked position.

Referring now to the drawings in detail, it will be seen that there is illustrated the forward portion ofa shotgun barrel 10 on which there is mounted the automatic choke attachment which is the subject of this invention, the automatic choke attachment being referred to in general by the reference numeral 12. Theautomatic choke attachment 12 includes a barrel member a 14 which may be considered either a barrel extension,

member or a barrel adapter. The barrel member 14'has a thin wall rear portion 16 which is telescope'cl over the forward end of the gun barrel 10 and is suitably'se cured thereto, either through means of a press fit or by welding. The barrel member 14 also includes a rcla tively thick forward portion 18 in which there is formed a plurality of circumferentially spaced, longitudinally ex tending slits 20 so as to divide the forward part of the barrel member 14 into a plurality of .deflectablefingers 22. Thus the choke of the barrel member 14 may be.

varied as is desired.

Disposed intermediate the relatively fixed forward portion 18 and a thin wall rear portion 16 are screw-threads: 24. Disposed immediately forwardly of the screwthreads 24 is an annular.. recess 26.. Normally seated in the annular recess aresplit halves 28 of a locking collar.

erence numeral 30. The operating- ;member ,SOiincltQ des.

7 34. Formed in the forwardportion 34on-the1uppeu' side thereof is an elongated guideway 36.which.-isrela-J i tively wide and *which terminates at -its'"rear endliina narrow longitudinal recess 38;" Projecting into the way 36 at the forward end thereof is a tab 40.

In the underside of theoperating:member 30gthcre is Telescoped over the 'barrel'member 14 and normally engaged primarily over the re portion v1 6 is an op.erat;-;. ingmember which is referredto in general by the ref-,

formed in the forward portion 34 adjacent the forward edge thereof an internally threaded bore 42. Also, formed in the rear part of the operating member 30 is an elongated cam slot .44, having an axis disposed at an angle to the longitudinal axis of the operatingmember 30. Seated in'the cam slot 44 is a pin 46 securely carried by the rear portion 16 of the barrel member 14. Thus as the operating member 30 moves longitudinally relative to the barrel member 14, the operating member 30 will be rotated. p

Threadedly engaged over the forward portion 18 of the barrel member 14 is a sleeve which is referred to in general by the reference numeral 48. The sleeve 48 has a generallyeonical interior projection 50 at the forward end thereof. The conical projection 50 engages with a reduced conical surface 52 on the forward end of the barrel member 14. Thus as the sleeve 48 is rotated and moved longitudinally of the barrel member 14, the choke of the barrel member 14 will be varied by the deformation of the forward portion 18 of the barrel member 14.

The sleeve 48 also includes a relatively thick rear portion 54. Formed in the rear edge of the rear portion 54 is a plurality of circumferentially spaced, generally triangular notches 56, 58, 60 and 62. The notches 56, 58, 60 and 62 are identical in configuration.

Slidably positioned in the guideway 36 is a drive finger which is referred to in general by the reference numeral 64. The drive finger 64 includes an enlarged rear portion 66 and a narrower forward portion 68 which terminates in an extreme forward part 70 which is complementary to the notches 56, 58, 60 and 62. Normally the forward part 70 is seated in one of these notches so as to retain the sleeve 48 in a fixed rotated position with respect to the barrel member 14.

The rear portion 66 of the drive finger 64 is seated in the guideway 36 and thus due to the engagement of the tab 40 with a shoulder 72 formed intermediate the rear portion 66 to the forward portion 68, the relative longitudinal movement between the operating member 30 and the drive finger 64 is limited. This, however, retains the drive finger 64 within the guideway 36.

The rear portion 66 of the drive finger 64 is provided with a recess 74 which is aligned with the recess 38 in the operating member 30. Seated in the recesses 38 and 74 is a spring member 76. The spring member 76 is in turn mounted on a rod 78 which extends into both the spring fingers 64 and the operating member 30. The spring 76 normally urges the drive finger 64 into engagement with the sleeve 48 and the operating member 30 rearwardly.

Carried by the operation member 30 is a tubular shield 80. The tubular shield is secured in place by means of a fastener 82 which is threadedly engaged in the internally threaded bore 42. The shield 80 encloses all of the operating mechanism of the automatic choke attachment 12.

Referring now to Figure 3 in particular, it will be seen that at the intersection between the rear portion 16 and the forward portion 18 of the barrel member 14 there is formed an internal shoulder 84. The shoulder 84 is spaced from theforward end of the shotgun barrel to form a shot expanding area 86.

In the initial position of the automatic choke attachment 12, the drive finger 64 is engaged in the notch 56. When the shotgun of which the shotgun barrel 10 is a part is fired, the backward force exerted on the breech of the shotgun by the gases in the shotgun barrel urges the shotgun barrel 10 to the rear very quickly. Since the operating member 30 is independent of the remainder of the automatic choke attachment 12 and the shotgun barrel 10, it will be seen that there will be relative movement between the operating member 30 and the barrel member 14 with the result that the resultant movement of the operating member 30 will be forwardly. Further,

because of the pin and cam slot connection between the operating member 30 and the barrel member 14, there will be a counterclockwise rotational movement of the operating member, as viewed from the rear end of the shotgun barrel 10. The drive finger 64 being seated in the notch 56, it will be seen that as the operating member 30 and the drive fingers 64 rotate in a counterclockwise direction, the drive finger 64 will rotate the sleeve 48 in a counterclockwisedirection and advance it rearwardly on the barrel member 14 thus to increase the choke of the barrel member 14.

As soon as the operating member 30 reaches the forward end of its travel, a spring member 76 will begin to urge the operating member 30 rearwardly with the result that it is rotated in a clockwise direction, as viewed from the rear end of the barrel 10, due to the pin and cam slot connection. At this time the expanding gases passing through the barrel member 14 act outwardly on the locking collar halves 28 to form a lock resisting the reverse rotation of the sleeve 48. Inasmuch as the mating surface of the drive finger 64 and the various notches 56, 58, 60 and 62 are .of the cam type, it will be seen that as the operating member 30 and the drive finger 64 rotate in a clockwise direction, the drive finger 64 will ride out of the particular notch in which it is positioned into the next notch with the sleeve 48 remaining stationary. The spring member 76 moves the operating member 30 back to its original position ready for the next firing of the shotgun. In order to indicate the position of the sleeve 48, there are formed on the forward part of the sleeve 48 a plurality of position identifying lines 90.

It is to be understood that each time the shotgun of which the shotgun barrel 10 is a part is fired, the sleeve 48 will be rotated one notch until the drive finger 64 enters into the last notch 62. When the drive finger 64 reaches this position, the continued firing of the shotgun will not rotate the sleeve 48 further due to the absence of additional cam surfaces.

From the foregoing, it will be readily apparent that there has been devised an extremely simple automatic choke attachment for shotguns. Furthermore, it will be readily apparent that the operating details of the automatic choke are such that the operation thereof is assured each time the shotgun is fired.

The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly all suitable modifications and equivalents may be resorted to, falling Within the scope of the invention as claimed.

What is claimed as new is as follows:

1. An automatic choke for shotguns comprising a barrel member having a discharge end, circumferentially spaced longitudinal slits in said discharge end and through the extreme end of said barrel member whereby said discharge end may be deformed to choke said barrel in varying degrees, a sleeve slidably mounted on said barrel member, said sleeve having a conical portion engaging said barrel member in the area of said discharge end and cooperating with said barrel member to deform said discharge end, an operating member slidably mounted on said barrel member rearwardly of said sleeve, first means interconnecting said operating member and said barrel member for rotating said operating member as said operating member moves longitudinally relative to said barrel member, a screw-threaded connection between said barrel member and said sleeve, and second means releasably connecting said operating member to said sleeve for turning said sleeve in one direction only as said operating member rotates back and forth, said second means including a plurality of notches in the rear edge of said sleeve and a forwardly projecting finger on said operating member cooperating with said notches to turn said sleeve, said notches each being generally triangular in outline and having a forward surface sloping rearwardly in the direction of rotation of said operating member when said operating member is moved rearwardly whereby said sleeve remains stationary when said operating member is moved rearwardly.

2. An automatic choke for shotguns comprising a barrel member having a discharge end, circumferentially spaced longitudinal slits in said discharge end and through the extreme end of said bar-rel member whereby said discharge end may be deformed to choke said barrel I in varying degrees, a sleeve slidably mounted on said barrel member, said sleeve having a conical portion engaging said barrel member in the area of said discharge end and cooperating with said barrel member to deform said discharge end, an operating member. slidably mounted on said barrel member rearwardly of said sleeve, first .means interconnecting said operating member and said barrel member forrotating said operating member as said operating member moves longitudinally relative to said barrel member, a screw-threaded connection be-- tween said barrel member and said sleeve, and second means releasably connecting said operating member to said sleeve for turning said sleeve in one direction only as said operating member rotates back and forth, said second means including a plurality of notches in the rear edge of said sleeve and a forwardly projecting finger on said operating member cooperating with said notches to turn said sleeve, said notches each being generally triangular in outline-and having a forward surface sloping rearwardly in the direction of rotation of said operating member when said operating member is moved rearwardly whereby said sleeve remains stationary when said operating member is moved rearwardly, the forward end of said finger being complemental to said forward surface.

3. An automatic choke for shotguns comprising a barrel member having a discharge end, circumferentially spaced longitudinal slits in said discharge end and through the extreme end of said barrel member whereby said discharge end may be deformed to choke said barrel in varying degrees, a sleeve slidably mounted on said barrel member, said sleeve having a conical portion engaging said barrel member in the area of said discharge end and cooperating with said barrel member to deform said discharge end, an operating member slidably mounted on said barrel member rearwardly of said sleeve, first means interconnecting said operating member and said barrel member for rotating said operating member as said operating member moves longitudinally relative to said barrel member, a screw threaded connection between said barrel member and said sleeve, and second means releasably connecting said operating member to said sleeve for turning said sleeve in one direction only as said operating member whereby said sleeve remains stationary when said operating member is moved rearwardly.

References Cited in the file of this patent,

UNITED STATES PATENTS 2,765,564 Schroeder Oct. 9, 1956 2,856,719 Metz Oct. 21, 1958 2,861,376 Denaux Nov. 25, 1958 2,864,194

Grahn Dec. 16, 1958 

